Tragedy: when the feeling’s gone and you can’t go on (Tragedy as performed by the Bee Gees. Spirits have flown, 1979.)

Here we describe loss of the feeling or emotion produced by music itself. Musical emotion can be considered at a number of
levels. At the most fundamental level, dissonance produces a perception that is unpleasant to most listeners.1 More variable is the intense pleasure that certain music may evoke in particular listeners, often described as a “shiver
down the spine” or “chills”,2 which is likely to represent a more complex aesthetic response. We describe a patient with selective loss of this emotional
response to music, due to a focal brain lesion.

A 52 year old right handed radio announcer collapsed in February 2000. He was found afterwards to have a total loss of speech
comprehension and output, and a right hemiplegia. His speech recovered well, such that 12 months after the event he had only
subtle output phonological problems. Motor functions recovered completely and he had no residual lateralising motor signs.
However, he reported a persistent alteration in his auditory experience. He was in the habit of listening to classical music,
to relax after working his night shift at the radio station, and had derived particular pleasure from listening to Rachmaninov
preludes. He experienced an intense, altered emotional state or “transformation” when he did this. In common with other subjects
who have this experience, the transformation was only produced by particular pieces, and he did not describe such an experience
in response to music other than Rachmaninov’s, nor to other sensory experiences. This emotional response to the music was
lost following the acute event, and remained absent during the period of testing between 12 and 18 months after the stroke.
During this period he was able to enjoy other aspects of life, and reported no biological features of depression. He had noticed
no change in his hearing, and was still able to identify speech, music, and environmental sounds normally.

When assessed in April 2001, pure tone audiometry, auditory filter widths,3 speech audiometry, prosody perception,4 and music perception were all normal. Musical perception was examined using a battery of tests during which subjects are
required to make same/different judgments on melody pairs that can show differences in melodic structure, rhythm, and metre.5 Our patient showed normal scores on tests of scale (28/30), contour (27/30), interval (28/30), rhythm (28/30), metre (29/30),
and incidental memory (27/30); see http://www.fas.umontreal.ca/psy/GRPLABS/lnmcg/website/index.html for normative data. Structural MRI revealed infarction involving the left insula and extending anteriorly into the left frontal
lobe and inferiorly into the left amygdala. After normalisation to the standard stereotactic space of Talairach, the infarcted
areas showed a close correspondence with left hemisphere areas activated during emotional response to music in normal subjects2 (fig 1).

In a case such as this it is impossible to prove that the stroke produced a new deficit in the emotional reaction to music
without direct evidence of the emotional reaction and its autonomic effect both before and after the stroke. The interest
of this investigation accrues from the subjective report of the patient alone. Nevertheless, this is the first documented
case of such a deficit of which we are aware, completing an important double dissociation between musical cognition and emotional
processing. Such a dissociation would require the presence of distinct substrates for musical cognition and emotion.

The cerebral basis for musical emotion has only recently been the subject of systematic study. In the clinical literature,
an impaired emotional response to music is generally accompanied by disordered musical perception (amusia). However, one previously
reported patient6 had impaired recognition of music despite a preserved affective response. In contrast, our patient strikingly illustrates
the reverse dissociation, with normal recognition of music but loss of the emotional response to music. Together, these two
cases complete a double dissociation between the perceptual and emotional components of music processing. This double dissociation
suggests that the emotional effect of a piece of music is not predetermined by simple acoustic properties (which were processed
normally in our patient).

Accumulating evidence from functional brain imaging studies in normal individuals suggests that functionally and anatomically
separable neural networks mediate music perception and emotion. The perception of music involves the superior temporal lobes
and inferior frontal lobes.7,8 In contrast, emotional processing of music engages a distributed brain network that is also recruited by other powerful emotional
stimuli that produce autonomic arousal. This network includes bilateral medial limbic structures, insula, ventral striatum,
thalamus, midbrain, and widespread neocortical regions.1,2 The present study enables us to conclude that the left insula is involved in normal musical emotional processing of music.

(A) Structural T1 weighted MRI sections of the patient’s brain in the coronal (left) and axial (right) planes, showing infarction
involving the left insula (black arrows) and amygdala (white arrows). (B) Coronal (left) and sagittal (right) T1 structural
sections have been used to demonstrate the correspondence between the left insula lesion in our patient and the left insula
activation associated with “chills” in response to music in normal subjects.2 Grey crosses showing the location of peak activation in the left insula of normal subjects have been superimposed on the
patient’s structural brain volume. The images from the patient were normalised to the common stereotactic space of Talairach
used in the previous functional imaging experiment2 to allow this comparison. The correspondence indicates that the left insula is necessary for a strong emotional response
to music.